Studies on processing and refrigerated storage of ‘Rista’

Meat Science 37 (1994) 347-368 © 1994 Elsevier Science Limited Printed in Great Britain. All rights reserved 0309-1740/94/$7.00

ELSEVIER

Studies on Processing and Refrigerated Storage of 'Rista'

Asgar H.

S a m o o n & N. Sharma

Division of Livestock Products Technology, Indian Veterinary Research Institute, Izatnagar-243122 (UP), India (Received 18 October 1991; revised versions received 14 June 1992 and 28 December 1992; accepted 15 May 1993)

ABSTRACT Effects of mutton fat levels, hot-boned versus cold-boned meat and manual versus machine mincing were studied on the quality of 'Rista' a popular emulsion type ground meat product of Kashmir (India). Incorporation of lamb fat at 20% level was found optimum for processing Rista. Both pre-rigor and chilled (post-rigor) meat were utilised for product manufacture. Addition of 0.5% sodium tripolyphosphate improved product binding, texture and yield. All these effects were more pronounced in machine minced Rista samples processed from cold-boned lamb meat, as compared with hot-processed and hand minced product. Cooked Rista was stored in low density polyethylene bags (0.25 tzm thickness) at 4 +_I°C in satisfactory condition for 4 days.

INTRODUCTION 'Rista' is a traditional emulsion type ground meat product of Kashmiri 'Wazawan', which represents the traditional cuisine consisting of several meat products processed on a large scale for feasts in the Kashmir valley of India, viz. 'Goshtaba', 'Nate-Yakhni', 'Aab-Gosh', etc. (Ansari, 1985; Samoon & Sharma, 1988). Rista emulsion is obtained by constant manual pounding of pre-rigor lamb meat and fat with a wooden hammer over a smooth surfaced and flat stone (Fig. 1). The meat emulsion so obtained is formed manually into spherical meat balls and cooked in a gravy flavoured with various spices and condiments. The product is served hot with boiled rice (Dar, 1977). 347

348

A. H. Samoon, N. Sharma

Fig. 1. Traditionalequipment used for processingRista.

The indigenous method of processing Rista is laborious, time consuming and less relevant to large scale hygienic production practices. Utilisation of pre-rigor lamb meat is considered obligatory in the traditional method which involves strict hot-processing schedules. There is no scientific literature available so far on processing and preservation of this product. Thus, keeping this in view, the present study was conducted to (i) develop an optimum recipe, (ii) standardise the processing schedule, (iii) assess the feasibility of incorporating chilled lamb meat and machine mincing for product processing, and (iv) evaluate the consumer acceptability and shelf-life of Rista during refrigerated (4 + 1°C) storage.

MATERIALS A N D METHODS Source of lean meat and fat

Male lambs, aged 6-9 months, of similar live weight (20-25 kg each) and conformation were purchased from the local market and slaughtered after 24 h fasting at the experimental abattoir of the Indian Veterinary Research Institute. The lambs were dressed and one side was deboned immediately to get the 'hot-boned lean' that was utilized for product processing within 2 h p o s t m o r t e m . The other side of the carcass was chilled at 4 + 1°C for 24 h, as per the conventional method, followed by deboning to get 'cold-boned lean'. Additional lamb fat was collected from

Studies on processing and refrigerated storage of "Rista"

349

freshly slaughtered lamb carcasses at the local market and chilled at 4°C overnight before use for product processing.

Product processing In a preliminary study, Rista samples were formulated to contain several levels of fat (15, 20, 25 and 30%) and evaluated by a sensory panel to determine the optimum level for juiciness, texture and overall acceptability of the product. Thus, 20% fat level was chosen as optimum for further experimental work as outlined in this paper. Chunks of lean meat were subjected to manual pounding using traditional equipment (Fig. 1). The lean meat was treated with salt (with or without polyphosphate) and pounded initially for 3 min. Chilled lamb fat was pounded separately along with large cardamom seeds for 2 min. Minced fat so obtained was incorporated in the lean meat at the desired level and pounding was continued together with half the total quantity of ice flakes for 5 min. The remaining ice was added and pounding conTABLE 1 General Formulation of Rista Ingredients I

II

Quantity (%)

Meat emulsion components (20%fat)

I part

Raw meat balls (10 x 50 g each) Sodium tripolyphosphate Crushed ice Salt Cardamom, ground Total

84.80 0-50 12.00 2.50 0-20 100-00

Gravy components

2 parts

Meat extract Vegetable oil Turmeric, ground Capsicum, ground Cardamom, cracked Cinnamon Cloves Ginger, ground Garlic Onion powder Colour, raspberry red Black pepper, ground Salt

87.00 4.50 1.40 1.50 0.10 0.20 0.02 0.20 0.50 2.50 0-05 0-03 2-00 100-00

Total

350

A. H. Samoon, N. Sharma

Hot-boned (pre-rigor) lean mutton

Fresh mutton fat

Heat to boiling /

Cut into chunks (2-2.5 sq. inch each)

Chill for 30 rains / L |

Mincing ~ - - I ~

~--~

L Add turmeric powder I Continue boiling for 10 min.

Mincing

Add hydrogenated vegetable oil, other spices and condiments

Mincing (lean + fat)

NaC1 and phosphate I

YI~,

l

[

Chilled water/ ] ice flakes

1

Large cardamon seeds Emulsion (Batter)

Shaped into spherical balls

Setting for 30 min (4 + I°C) Rista-Gravy Reshaping of meat balls

I Cook meat balls in gravy for 25 min (at boiling point)

Sprinkle with black pepper powder

I Serve hot for organoleptic evaluation Fig. 2.

Refrigerate (at 4 +_I°C) in LDPE bags. Rewarm and serve for organoleptic evaluation Processing of RISTA.

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351

tinued for a further period of 3 min to achieve an emulsion of desirable consistency. It was formed manually into spherical meat balls weighing 50 g each, which were chilled at 4 + 1°C until cooking. Gravy was simultaneously processed, to which meat balls were added and cooked for 25 min to get the finished product. The standardised processing schedule indicating sequence of addition of ingredients and the recipe are outlined in Fig. 2 and Table 1, respectively. To compare the effects of hot-boning versus cold-boning and hand pounding versus machine mincing, lean meat and fat components were passed through the 8 m m plate followed by the 4 mm plate of a grinder (Hobart Model 4812) and chopped for 8 min in a food cutter (Hobart Model 841820) along with the other ingredients. Half the ice flakes were added at the start of chopping and the remaining ice was added after the first 5 min of chopping. Sodium tripolyphosphate was added (0.5%) in both hot-processed and cold-processed samples along with 2.5% salt. Control samples contained 2-5% salt alone.

Product analysis and storage studies Appropriate portions of meat emulsion and finished product were collected for analysis. The product was served hot to a group of seven experienced panelists for sensory evaluation on an eight-point hedonic scale (8 = extremely desirable, 1 = extremely undesirable) for appearance, flavour, juiciness, texture and overall acceptability (Stone & Sidel, 1985). The emulsion pH was recorded by the method of Young et al. (1987) and emulsion stability by the method of Baliga & Madaiah (1971). Proximate composition of meat balls, i.e. moisture, ether extract, protein and total ash, were evaluated by AOAC methods (nos. 24.003, 24.005, 24.027 and 24.062, respectively; AOAC, 1980). Appropriate portions of finished product consisting of meat balls soaked in gravy were sealed in low density polyethylene (LDPE) bags of 0.25/zm thickness and stored at 4 + I°C. Samples were taken on the 1st and 4th days of storage to determine pH by the m e t h o d of Koniecko (1979) and TBA values, as per Tarladgis et al. (1960). Aerobic plate counts were taken on the 1st, 2nd, 4th and 7th days of storage, as per ICMSF (1978). Sensory evaluation of the product was also performed on the 4th day of storage as described above for the fresh product.

Statistical analysis of data Experiments were conducted as shown in Fig. 3. The data obtained for various fresh product quality attributes were subjected t0 analysis of

352

A. H. Samoon, N. Sharma

Lamb (Sheep)

I Slaughter and Dress

Split into two sides [ . . . . . . . . . . . . . . . . . . .

V .................

1

[

HB one side (within 1 h PM)

/

Chill (4 + 1°C/24 h) and CB other side

I

I

I

PRODUCT PROCESSING (within 2 h PM)

r .........

. . . . . . . . .

TM

F. . . . ST

J. . . . .

PRODUCT PROCESSING (24 h PM)

1

F. . . . . . . .

MM

I

F. . . .

PT

ST

I. . . . .

L . . . . . . . . .

TM

l PT

F. . . .

L___

ST

1

PT

1

MM

F. . . .

]. . . .

ST

l PT

Fig. 3. Experimental design. HB : Hot-boning; CB : cold-boning; T M : traditional mincing; M M : machine mincing; ST : salt treated; PT : salt and phosphate treated, Product : Rista

variance in a 2 × 2 × 2 factorial design, using the following statistical model:

Yokl = tz + ai + 1~j + Yk + (a~)ij + (ay)ik + (t~Y)jk + (a1~Y)ijk + eijkt Similarly, the d a t a o b t a i n e d d u r i n g storage studies were subjected to analysis o f variance in a 2 x 2 x 2 x 2 factorial design, using the following statistical model: YiJ'klm = ]'£ q- Oli q- ~ j -{- "~k q- ¢~l -I- (Ol[3)ij q- (Ol'Y)i k q- (0l¢~)i l

+

+ (gs)jl + (es) l + eo lm

where ai c o n d i t i o n 1, 2 /3j m i n c i n g 1, 2 7k t r e a t m e n t 1, 2 61 storage 1, 2 error ( N I D ) 0, o-z T h e analysis o f variance was c o n d u c t e d a c c o r d i n g to Snedecor & C o c h r a n (1968). All significant m a i n effects a n d interactions were tested using the least significant difference test as per Steel & Torrie (1980) a n d are discussed in the following text.

Studies on processing and refrigerated storage of 'Rista'

353

RESULTS AND DISCUSSION

Fresh product quality The results obtained for various fresh product quality characteristics are discussed below. (i) Emulsion p H

The mean pH values of raw emulsion samples are presented in Table 2 and results of their ANOVA are given in Table 3. Hot-boned emulsion had a significantly (P < 0.01) higher pH compared with cold-processed samples, which is well-documented. The lower pH associated with hand mincing observed in the present study might be due to delayed product processing as compared with machine mincing with a resultant greater fall in pH. The effect of mincing period in increasing the rate of pH has also been reported by Bendall (1978). However, it appears that addition of polyphosphate enhances the emulsion pH significantly (P < 0.01), irrespective of the type of mincing employed, which is in agreement with the findings of Kondaiah & Sharma (1988) in goat meat patties. (ii) Emulsion stability

Mean values for the emulsion stability test are presented in Table 2 and the results of ANOVA in Table 3. It was observed that hot-processed emulsion samples had a significantly (P < 0.01) higher emulsion stability with lower cooking loss compared with their cold-processed counterparts; this is due to the superior water and fat binding properties of prerigor meat, which have been well documented. Cross et al. (1979) have also reported similar findings in ground beef. Traditionally processed emulsion samples were also significantly (P < 0-01) more stable than machine minced samples, due to impact energy imparted by traditional pounding leading to better myofibrillar protein extraction and fat dispersion into the protein matrix. Maesso et al. (1970), Theno et al. (1978) and Samoon & Sharma (1991) have reported similar findings in meat emulsions subjected to identical treatments like beating, massaging, tumbling and manualpounding. On the other hand, lamb fat might not have dispersed so thoroughly in machine mincing (Chattoraj et al., 1979). However, addition of sodium tripolyphosphate significantly (P < 0.01) improved emulsion stability of such samples, by improving the functional properties of the meat (Sofos, 1986). Phosphates also prevent protein denaturation and increase stability of proteins in the hydrated state (Steinhauer, 1983), which are mobilised to coat the fat in the emulsion (Schwartz et al., 1985).

6-07 + 5.90 + 5.93 + 6-04 + 5.91 + 6.06 + 5~97 + 6.10 + 6.07 + 6.13 + 5.74 + 5.92 + 5.87 + 6.08 +

HB CB TM MM ST PT H B T M ST HB T M PT H B M M ST HB M M PT CB T M ST CB T M P T CB M M ST CB M M P T

7.69 14.84 9.21 13.32 12.38 10.15 7.12 5.72 10.37 7.53 13.13 10.85 18.89 16.48

+ 0.84 + 1-54 + 1-47 • 2-28 + 2-16 + 2.05 + 0.26 -~ 0-22 + 0.53 z 0.16 + 0-45 _+ 0.23 z 0.15 _~ 0-30

Emulsion stability c% cooking loss) 106.66 94.86 103.95 97.56 98.72 103.95 109.80 113.80 96.57 106.45 95.27 96.93 93.23 94.00

+ + + + + + + + + + z + z +

3.19 0.70 4.00 1.32 3.25 3.92 1.06 b 1.27 a 0.32 a 1.18 C 0.37 a 0-44 de 0.46 af 0.41 df

Percent cooking yieM 65.32 65-40 64.86 65.92 65.28 65.49 64.05 65.52 66.15 65.63 64.83 65.03 66.12 65.77

+ + + + + + + + + + + + + +

0.39 0.26 0.26 0.11 0.44 0.14 0.13 a 0.12 b 0.16 a 0.04 b 0.15 c 0.03 c 0-07 ~ 0.05 b

Percent moisture

16.27 17.36 16.47 17.43 17.45 16.45 16.61 14-84 17-01 16.61 17.42 17.01 18.74 17.35

+ 0.42 + 0.33 + 0-47 z 0.40 z 0-40 + 0.48 _+ 0.20 b + 0.12 a + 0.05 bC + 0-20 c + 0.12 bc + 0.05 b~ + 0.75 a + 0.08 c

Percent protein

15.79 14.03 15.10 13.33 13.99 15.14 16.52 16.67 12-55 14.66 14.82 15-16 12.06 14-07

+ + + + + + + + + + + + + +

0.84 0.60 0.46 0-53 0.90 0.48 0.12 0.08 0.09 0.15 0.12 0.10 0.05 0.04

Percent ether extract

M e a n s in each c o l u m n with a c o m m o n superscript for each p a r a m e t e r are n o t significantly different (P < 0-05). Differences in m e a n s of m a i n effects, i.e. HB vs CB, T M vs M M a n d ST vs PT. are s h o w n in A N O V A results, vide Table 3. G l o s s a r y o f terms a n d abbreviations given in A p p e n d i x

0.03 0.06 0.06 0.05 0.06 0.04 0.06 0.07 0.08 0.07 0.06 0.06 0.05 0.03

Emulsion pH

Treatments

TABLE 2

M e a n s a n d SE o f F r e s h P r o d u c t Quality Characteristics o f R i s t a

2.81 2.80 2.80 2.81 2.81 2.80 2.82 2.97 2.81 2.82 2.80 2.78 2.81 2.79

+_ 0.03 + 0-01 + 0.03 ___0.01 + 0.00 + 0.04 + O-O4 _+ 0.01 + O-O2 + 0.02 + 0.02 +_ 0.01 + 0.01 + 0.01

Percent total ash

L~

Studies on processing and refrigerated storage of 'Rista"

355

Interaction between condition and mincing was significant (P < 0.01) and emulsion stability was better in HBTM samples with a lower cooking loss (CL; 6-42%) compared with HBMM samples (CL; 8.95%). Similarly, samples of CBTM emulsion were more stable (CL; 11.99%) than CBMM emulsion (CL; 17.69%). This is due to a more pronounced effect of traditional mincing in improving the binding of cold-processed sampies compared with the hot-processed group of emulsions. On the other hand, it appears that binding and stability of hot-processed emulsions is superior, even in machine minced samples, and hand mincing caused only a marginal improvement. Similar findings were reported by Samoon & Sharma (1991) for 'Goshtaba'. (iii) Cooking yield

The mean values of percent cooking yield of Rista samples subjected to various treatments are presented in Table 2 and the results of ANOVA in Table 3. The higher (P < 0.01) cooking yield of hot-processed Rista samples as compared with cold-processed samples is in agreement with findings reported by Cross et al. (1979) and Jacobs & Sabranek (1980) in ground beef patties. Cooking yield was higher (P < 0.01) in hand minced than in machine minced product, which correlates well with the findings reported for the emulsion stability test. Manual pounding of meat causes better myofibrillar protein extraction, fat emulsification and product binding with lower fat losses into the gravy upon subsequent cooking as compared with machine mincing. Maesso et al. (1970) and Theno et al. (1978) have also used similar treatments like beating, massaging and tumbling to improve the functional properties of meat. The effect of polyphosphate in increasing the product yield was due to the increase in water holding capacity and improved product binding in the treated samples. Similar findings have been reported by Molins et al. (1987) in ground beef patties. A significant (P < 0-01) interaction between condition and mincing revealed that cooking yield was significantly (P < 0.05) higher in HBTM Rista balls (111.80%) as compared with HBMM balls (101.51%). Similarly cooking yield was significantly (P < 0-05) higher for CBTM Rista (96-10%) than CBMM product (93-62%). However, differences in means were greater in the case of cold-processed Rista samples obtained by both traditional and machine mincing, due to a more pronounced improvement in cooking yield of cold-processed product by traditional mincing. However, traditional mincing had only a marginal effect in further improvement of the yield of hot-processed Rista. Interaction between condition and treatment was significant (P < 0.01) and cooking yield was significantly (P < 0.05) higher for HBPT samples

24

Error

0.343

0.211"* 0.090* 0.168"* 0.014 0-021 0-001 0.005

MSS

16

1 1 1 1 1 1 1

df

0.298

307.030** 101.520"* 29.930** 14.980"* 0.070 0.930 0.630

MSS

Emulsion stability (% cooking loss)

**P < 0.01, *P < 0.05. Glossary of terms and abbreviations given in Appendix.

1 1 1 1 1 1 1

df

Emulsion pH

Between conditions Between mincings Between treatments Condition × mincing Condition × treatment Mincing × treatment Condition × mincing × treatment

Sources of variation

232

1 1 1 1 1 1 1

df

20.730

8 349.68** 2 447.370** 998.780** 914.160"* 4t9.930"* 93.26* 172.710"*

MSS

Percent cooking yield

16

1 1 1 1 1 1 1

df

0.035

0.058 6.742** 0.244* 0.014 0.448** 2-444** 2.778**

MSS

Percent moisture

16

1 1 1 1 1 1 1

df

0.103

11.111"* 5.501"* 5.930** 0.095 0.048 0.059 2.094**

MSS

Percent protein

TABLE 3 Results of Analysis of Variance of Fresh Product Quality Characteristics of Rista

16

1 1 1 1 1 1 1

df

0.023

36.210"* 6.910"* 7.930** 1.720"* 4.940** 0.010 0.050

MSS

Percent fat

16

1 1 I 1 t 1 1

df

0.002

0.001 0.000 0.001 0.000 0.000 0.000 0.000

MSS

Percent total ash

Studies on processing and refrigerated storage of "Rista'

357

(110-13%) compared with HBST samples (103-18%) of Rista balls. Cooking yields were also higher for CBPT Rista balls (95.47%) than CBST balls (94.25%), but the differences were non-significant. It appears that polyphosphate is more effective in improving the cooking yield of hot-processed Rista compared with cold-processed product. Kondaiah & Sharma (1988) have also reported higher cooking yields in hot-processed as compared with cold-processed goat meat patties treated with polyphosphate. Interaction between mincing and treatment was significant (P < 0.05) and the average cooking yield was significantly (P < 0.05) higher for TMPT samples (105-37%) than TMST samples (102-53%). Similarly, a higher yield was obtained for MMPT samples (100.23%) compared with MMST samples (94-90%). Thus, it can be inferred that the effect of phosphate in improving the cooking yield is more pronounced in the case of hand minced samples than in machine minced samples. As already discussed above, traditional mincing causes better myofibrillar protein extraction and working of the solubilised proteins of the matrix into the disrupted and loose structured muscle fibres. This effect appears to be supplemented by the presence of salt and phosphate, which improves the emulsifying capacity of the extracted proteins resulting in better entrapment of fat globules and thus a more stable emulsion. On subsequent cooking, less fat escapes into the gravy and a higher yield is obtained. On the other hand, phosphate improved the yield of machine minced Rista balls too but the effect was only marginal compared with that obtained in hand minced product. A significant (P < 0-01) interaction between condition, mincing and treatment was also observed in the cooking yields of Rista samples and the differences in means are shown in Table 2. In general, the yields were higher for hot-processed, hand minced and phosphate treated samples compared with the cold-processed, machine minced and salt treated product, due to the improvement of emulsion stability, better fat retention and product binding in the former groups of product samples as compared with their respective counterparts. (iv) Proximate composition

(a) Moisture. The data on proximate composition (percent moisture, protein, ether extract and total ash) are presented in Table 2. The analysis of variance of the data (Table 3) suggests that condition (hot versus chilled) of meat had no significant effect on moisture levels of the product. However, in general, machine minced Rista samples retained significantly (P < 0-01) higher moisture levels than hand minced samples, due to better fat retention and a corresponding drop in moisture levels on a percentage basis in the latter as compared with the former group of samples.

358

A. H. Samoon, N. Sharma

Interaction between condition and treatment was significant (P < 0.01) and the moisture content was higher in phosphate treated samples (65.58%) than in their controls (65.10%) for hot-processed product. However, the differences were non-significant between salt treated (65-47%) and phosphate treated (65.40%) product samples of cold-processed Rista. This can be attributed to a supplementary effect of phosphate in improving moisture retention of hot-processed Rista samples, by increasing pH and water holding capacity of pre-rigor meat more effectively. These findings correlate well with the cooking yield data discussed above. Interaction between mincing and treatment was significant (P < 0.01) and the moisture content was significantly (P < 0.05) higher in hand minced samples treated with phosphate (65-28%) compared with their controls (64.44%). On the other hand, moisture content was slightly lower in machine minced samples treated with phosphate (65.70%) compared with the control samples (65-90%). This is obviously due to the more uniform distribution of added phosphate and thus improved fat retention in hand minced product with a resultant drop in moisture content on a percentage basis. However, further investigation is required to establish such findings. Interaction between condition, mincing and treatment was significant (P < 0.01) and variations in moisture content between various treatments are depicted in Table 2. It can be observed that moisture content was lower in phosphate treated samples compared with the salt treated counterparts in both hot- and cold-processed groups of Rista samples subjected to machine mincing. Such differences may be attributed to better fat retention associated with addition of polyphosphate with a corresponding drop in moisture content of Rista on a percentage basis. On the other hand, differences in moisture content between phosphate treated Rista samples and their controls in machine minced product processed from chilled meat were non-significant but moisture level was significantly (P < 0.05) lower in hand minced and hot-processed samples treated with phosphate compared with their controls. The possible explanation for such a trend could be that hand mincing and phosphate treatment might have a synergistic effect in improving both fat and moisture retention in the product samples, which needs further investigation. (b) Fat. In general, hot-processed and hand minced groups of Rista samples retained more fat (P < 0.01) than their cold-processed and machine minced counterparts. Addition of phosphate also improved fat retention in treated samples compared with controls but the effect was more pronounced in the cold-processed product, which correlates well with the findings on cooking yield discussed above. It also appears that a

Studies on processing and refrigerated storage of 'Rista'

359

substantial drop in fat levels from 20% formulated in the raw emulsion to about 12-16.5% in the finished product resulted due to losses of fat into the gravy during cooking of Rista. Such losses of fat into the gravy may appear higher than for other western meat products processed by dry heating methods but are considered optimum in the traditional processing of Rista. It can be observed from the data presented in Table 2 and the results of ANOVA (Table 3) that, in general, protein levels were significantly (P < 0.01) lower in hot-boned, hand minced and phosphate treated samples compared with their cold-processed, machine minced and salt treated counterparts respectively. Such a trend can be attributed to a proportionate drop in protein levels of the former group of samples on a percentage basis, associated with better fat retention, compared with the latter group of Rista samples. (c) Protein. A significant (P < 0.01) interaction observed between condition (hot versus chilled), mincing (hand versus machine) and treatment (salt versus phosphate) revealed that phosphate treated samples contained significantly (P < 0-05) lower protein levels compared with salt treated samples in both hot-processed and hand minced as well as coldprocessed and machine minced groups of Rista samples. Protein content was also lower in phosphate treated samples compared with the salt treated counterparts in both hot-boned and machine minced as well as cold-boned and hand minced groups of cooked Rista balls. However, the differences in the mean values of the latter two groups of samples were non-significant. These variations in protein content correspond well with the changes in fat levels of the product samples subjected to different treatments. The proportionate drop in protein levels with increase in fat retention is similar to findings reported by Keeton (1983) in pork patties. However, protein levels were above the minimum prescribed standards for various meat products (McKenzie, 1964). (d) Ash. There were no significant differences in the total ash contents of various Rista samples.

Quality changes duringstorage Mean values of product pH, TBA values and aerobic plate counts for Rista samples subjected to refrigerated storage are presented in Table 4 and the results of ANOVA are given in Table 5. (i) Product pH In general, a higher pH (P < 0-01) was recorded in hot-processed samples (6.26) than cold-processed samples (6.04) of Rista. A similar trend was observed by Jacobs & Sabranek (1980) in ground beef patties

T M ST T M PT M M ST M M PT T M ST T M PT M M ST M M PT

+ + + + + + + +

0.01 0.03 0.12 0.03 0.04 0.02 0.03 0.04

6.07 a + 0.02

6.13 6.25 6.12 6.24 5.90 5.99 5.90 6.00

Day 1

pH

+ + + + + + + +

0.02 0.01 0.01 0.02 0.01 0.03 0.02 0.01

6.23 b + 0.04

6.30 6.37 6.28 6.38 6.08 6.15 6.10 6.18

Day 4 + 0.013 + 0.000 + 0.134 _+ 0.026 + 0.045 + 0.022 + 0.022 + 0.026

0.136 a + 0.017

0.091 0.078 0.169 0.104 0.234 0.156 0.156 0.104

Day 1 0.034 0.045 0.026 0.045 0.045 0.047 0.069 0.045

0.418 b + 0.061

+ + + + + + + +

Day 4 0.572 0.286 0.325 0.286 0.390 0.294 0.806 0.390

TBA values I

+ 0.21 + 0.15 + 0.18 + 0.12 + 0.19 + 0.09 + 0.18 _+ 0.19

4.08 u + 0.03

4.16 4.15 4.08 4.00 4.22 3.97 4.11 3.94

Day 1 + + + + + + + +

0-16 0.18 0.15 0-11 0.12 0.09 0.71 0.21 4.28 b + 0.02

4.35 4.20 4.35 4.30 4.31 4.25 4.31 4.20

Day 2

+ 0.12 + 0.14 + 0.14 + 0-10 + 0-09 + 0.13 + 0.24 _+ 0.21 4.55 C+ 0.04

4.70 4.50 4.66 4.42 4.65 4.45 4.61 4.39

Day 4

Aerobic plate counts (log~g)

Overall means in each horizontal row with c o m m o n superscripts for each parameter are not significantly different (P < 0.05). I mg melanoldehyde per kg o f product. Glossary o f terms and abbreviations given in Appendix.

Overall means

HB HB HB HB CB CB CB CB

Treatments

TABLE 4

M e a n s and SE o f Quality Characteristics o f Rista during Storage

+ + + + + + + +

0.15 0-14 0.18 0-23 0.15 0.17 0.31 0.23 5.34 a + 0.01

5.40 5.35 5.34 5.29 5.38 5.30 5.36 5.32

Day 7

361

Studies on processing and refrigerated storage of "Rista' TABLE 5

Results of Analysis of Variance of Quality Characteristics of Rista during Storage pH

Sources of variation df

TBA values (mg rnelanoldehyde/kg) MSS

df

MSS

Aerobic plate counts (log~g) df

MSS

Between conditions Between mincings Between treatments Between storage days Condition X mincing Condition x treatment Condition x storage Mincing x treatment Mincing x storage Treatment x storage

1 1 1 1 1 1 1 1 1 1

0.587** 0-000 0.105"* 0.322** 0.001 0.001 0-003 0.000 0.000 0-002

1 1 1 1 1 1 1 1 1 1

0-073 0.010 0.203* 0.959** 0.051 0-010 0.008 0.002 0.015 0-073

1 1 1 3 1 1 3 1 3 3

0.022 0.042 0-361" 7.360** 0.001 0.009 0-001 0.001 0.012 0.028

Error

37

0.002

37

0.044

77

0-073

**P < 0.01, *P < 0.05. Glossary of terms and abbreviations given in Appendix. and by S a m o o n & Sharma (1991) in ' G o s h t a b a ' . Phosphate treated samples had a higher p H (6.20) c o m p a r e d with the salt treated samples (6-10), which is in agreement with the findings o f Schults et al. (1972). The p H increased significantly (P < 0.01) during storage due to release o f alkaline metabolites by proliferating microflora into the p r o d u c t (Jay, 1986). Various interactions were non-significant. (ii) T B A values It was f o u n d that T B A values were significantly (P < 0.05) lower in p h o s p h a t e treated samples (0.213) than in the controls (0-263). Although sodium tripolyphosphate was added to improve p r o d u c t binding and texture, its antioxidant effect observed in this study is in agreement with the findings o f M a t l o c k et al. (1984) and King & Earl (1988) in other ground meat products. T B A values increased significantly (P < 0-01) from the 1st day (0.239) to the 4th day (0-317) o f storage, due to the onset o f mild oxidative rancidity in the product (Reagan et al., 1983; R a v i n d r a n a t h et al., 1988). (iii) Aerobic plate counts Aerobic plate counts showed that, overall, microbial loads o f the product did n o t exceed 5.40 log/g during 7 days o f refrigerated storage at 4 _+ 1°C. Nevertheless, the counts increased significantly (P < 0.01) during storage.

Day 4

6.94a-+0-11

7.24+0.15 7.19+-0-18 7.00 + 0-14 7-29+-0.14 6.48+-0.19 6.95_+0.16 6.43+-0.18 6.95 _+0.16

Day 1

5-149+0-27

4.81 ---0.16 5.57+-0.24 4-24 _+0.24 6.48-,-0.73 4-81_+0.13 5.90+0.18 4-09+-0.18 5.19 _+0.25

Day 4

Flavour

6"81a+0.27

6.95+0.15 7.09+-0-12 6.81 + 0-13 7.10+0.14 6.48_+0.15 7.00+0.14 6.19+-0.13 6.86 _~0.14

Day 1 6.95+0.15 7-19+0-16 6.67 + 0.13 7.24+0.19 6.43+-0.19 7-05+-0.13 6.00_+0.14 6.90 +- 0.14

Day 1

Day 4

6"18b+0.14

6.57_~0.16 6.71 +0-10 5-90 + 0.12 6.29+0.16 6.14_+0.13 6.52_+0-11 5.52_+0.31 5.81 + 0.19

Texture

6"159__.0.09 6"80a+0'14

6.29+0.10 6.57__x0-11 6.10 +- 0.10 6-48z0.11 5.95+-0.15 6.19z0.13 5.81+-0.16 5-81 +- 0.16

Day 4

Juiciness

Means in each horizontal row for each parameter bearing a common superscript are not significantly different (P < 0-01). Glossary of terms and abbreviations given in Appendix.

646 b+0.10

7.52+0.13 6.81z0.09 7-48+0-11 6.90+0-07 7.14 +- 0.14 6-38 _+0.13 7-29 z0-12 6.67+0-11 6.81_+0-16 6.24_+0-11 7.10+0.15 6.38z0.13 6.52+-0.15 6.05z0.11 7.05 z 0.14 6.29 _+0.14

Day 1

Appearance

Overall means 7.11a i- 0.11

HBTMST HBTMPT HB MM ST HBMMPT CBTMST CBTMPT CBMMST CB MM PT

Treatments

TABLE 6

Means and SE o f Sensory Scores for Various Treatments o f Rista during Storage

5.29+-0.17 5-67+-0.28 4-52 +- 0.20 5.48_+0.24 5.00+0.19 6.24+-0.15 4.24_+0.21 5.14 + 0.19

Day 4

6-76a + 0.14 5"20b + 0.91

7.00+_0.14 7-14+0.16 6.57 +- 0.13 7-14_+0-16 6.29_+0.18 7-00+-0.14 6.00z0.12 6.95 + 0-13

Day 1

Overall acceptability

t~

363

Studies on processing and refrigerated storage of "Rista"

Condition (hot versus chilled) and mincing (hand versus machine) had no significant effect but, in general, phosphate treated samples showed a lower (P < 0.01) average count (4-50) compared with salt treated controls (4.62). The antimicrobial effect o f phosphates has also been reported by Molins et al. (1987) in beef patties and by M a r c y et al. (1988) in pork sausages. However, further investigation is needed to establish the antimicrobial effect o f phosphate in Rista. (iv) Sensory quality The m e a n values for various sensory quality attributes, i.e. appearance, flavour, juiciness, texture and overall acceptability for the fresh product and on the 4th day o f storage are presented in Table 6. The results of A N O V A (Table 8) show that the main effects, i.e. condition (hot versus chilled), mincing (hand versus machine) and treatment (salt versus phosphate), were significant and their mean values are reported separately in Table 7. (a) Appearance. Higher appearance scores of hot-processed Rista samples were due to a more desirable colour, greater swelling, improved binding and a more uniform cross-sectional appearance o f these samples compared with their cold-processed counterparts. C h u et al. (1987) reported similar findings in restructured beef steaks. Similarly, better fat retention and thus a lesser a m o u n t o f visible fat particles might account for the better appearance of hand minced compared with machine minced product. Addition of polyphosphate improved the appearance scores, in agreement with the findings o f Neer & M a n d i g o (1977) in restructured pork patties, H u f f m a n et al. (1981) in hamburger patties and R a v i n d r a n a t h et al. (1988) in buffalo and pork blend sausages.

TABLE 7 Means -~ SE of Various Main Effects of Sensory Scores for Rista during Storage Effect

Appearance

Flavour

Juiciness

Texture

Overall acceptability

HB CB TM MM ST PT

7.02 :t: 0.13 6.55 ± 0.13 6-90 _+0-15 6.67 ± 0.15 6.68 + 0.16 6-89 +_0.14

6.23 + 0-40 5.85 + 0.06 6.12 + 0.33 5.96 + 0-42 5-64 _+0.35 6-44 _+0.26

6.67 + 0.12 6-29 _+0-15 6-56 + 0.14 6.39 -+ 0.16 6.32 + 0.13 6-64 _+0.15

6.69 + 0.15 6.30 + 0.17 6.70 _+0-12 6.29 -+ 0.20 6.27 + 0-15 6.71 + 0.16

6.10 + 0.33 5.86 + 0.32 6-20 + 0.27 5.76 + 0-36 5-61 _+0-33 6.35 _+0.27

For levels of significance, see ANOVA results (Table 8). Glossary of terms and abbreviations given in Appendix.

364

A. H. Samoon, N. Sharma

TABLE 8

Results of Analysis of Variance for Sensory Scores of Rista during Storage Source of variation

Between conditions Between mincings Between treatments Between storage days Condition x mincing Condition × treatment Condition × storage Mincing × treatment Mincing × storage Treatment × storage Error

df

1 1 1 1 1 1 1 1 1 1 325

Appearance

Flavour

Juiciness

18.570"* 11-810"* 12.570"* 4.530** 2.170"* 2.500* 3.650** 54.140"* 8.360** 35-360** 273.140"* 36-670** 0.500 3.650 0.370 0.670 0.006 0.150 0.030 0.860 0.080 0.660 4.530 0.030 0-000 1.080 0.080 0.020 20.510 0-670 0.338

1.380

0.380

Texture

Overall acceptability

12-960"* 5.000** 13.760"* t6.740"* 16-300"* 45-030** ~2.190"* 205-860** 0-430 0.860 0.970 4.070* 0-050 2.170 0.170 1.070 3-440** 5-500** 1-710 1-570 0.443

0.674

**P < 0.01, *P < 0-05. Glossary of terms and abbreviations given in Appendix. The decrease in appearance scores during storage was due to the onset o f slight dullness in surface colour o f the product as well as an associated d r o p in its flavour scores on the 4th day o f storage, which might have indirectly influenced the scores for other attributes by the taste panel members. (b) Flavour. H o t - p r o c e s s e d Rista samples received better flavour scores than the cold-processed counterparts, and hand minced groups o f p r o d u c t samples were rated superior in flavour to the machine minced samples. Better fat retention and juiciness in hot-processed and hand minced groups might have indirectly caused perception o f improved flavour in these samples c o m p a r e d with cold-processed and machine minced samples respectively. I m p r o v e m e n t o f flavour by addition o f p o l y p h o s p h a t e observed in this study is similar to findings reported by H u f f m a n et al. (1981) in hamburger patties. It might be due to the action o f p o l y p h o s p h a t e in moderating the pro-oxidant effect o f sodium chloride (Keeton, 1983), thereby enhancing the sensory properties o f the product. Deterioration o f p r o d u c t flavour, as depicted by a drop in scores, due to the onset o f oxidative rancidity o f the p r o d u c t associated with the increase in T B A values, was the main factor limiting the shelf-life o f Rista during refrigerated storage. Thus, the scope for use of antioxidants and other additives in use for various other meat products to control oxidative rancidity o f Rista needs further investigation.

Studies on processing and refrigerated storage of 'Rista"

365

A significant (P < 0.01) interaction between treatment and storage revealed that the average flavour score of phosphate treated samples (7.10) was not significantly different from salt treated samples (6-79) of fresh product. However, the differences became significant (P < 0-05) on the 4th day of storage, with higher scores for the former group (5.79) compared with the latter group of samples (4-49), which reflects a more rapid drop in flavour scores due to the pro-oxidant effect of sodium chloride (Neer & Mandigo, 1977) in the salt treated group of samples. (c) Juiciness. Hot-processed Rista samples were more juicy (P < 0.01) than the cold-processed samples, in agreement with the findings of Cross et al. (1979) and Jacobs & Sabranek (1980) in ground beef patties. Similarly, hand mincing and addition of polyphosphate significantly (P < 0.01) improved product juiciness. This may be attributed to better fat retention in these samples, which is in agreement with the findings on proximate composition discussed above. A progressive drop in juiciness scores during storage probably reflects an associated decline in scores for other attributes of the product. (d) Texture. Higher texture scores associated with hot-processing of the product resulted due to better myofibrillar protein extraction and improved product binding associated with use of pre-rigor meat (Schmidt & Trout, 1984). Furthermore, Jacobs & Sabranek (1980) also reported similar findings in ground beef patties. Similarly, improved texture due to hand mincing observed in this study was identical to similar effects associated with treatments like massaging, tumbling and beating employed by Maesso et al. (1970) and Theno et al. (1978) in meat emulsions. Addition of polyphosphate significantly (P < 0.01) improved product texture. Moore et al. (1976) and Huffman et al. (1981) have reported similar findings in beef rolls and hamburger patties, respectively. Texture scores dropped significantly (P < 0-01) during storage. There was a significant (P < 0-01) interaction between mincing and storage. The mean texture scores dropped in hand minced Rista samples from 6.90 on the 1st day to 6.49 on the 4th day. Similarly, the scores of machine minced product dropped from 6.70 (day 1) to 5.80 (day 4). Similar results were reported by Anjaneyulu (1988) in buffalo meat patties. However, the drop in texture scores was greater in the machine minced samples than in the hand minced group of Rista samples, which may be attributed to a more rapid ingress of moisture from the surrounding gravy into the machine minced Rista balls with a resultant softening of the product texture. On the other hand, the emulsion was more stable and compact upon cooking in the hand minced group, which resisted moisture aborption. These findings correlate well with those reported on proximate composition in this study.

366

A. H. Samoon, N. Sharma

(e) Overall acceptability. Taste panel findings of Rista suggest that, in general, hot-boned, traditionally minced and phosphate treated Rista samples were significantly (P < 0.01) superior in terms of overall acceptability compared with their cold-processed, machine minced and salt treated counterparts, respectively. However, sensory scores for the latter groups of samples were also found to be well within the moderately to highly acceptable range. Overall acceptability of the product dropped during storage (Table 6), with detectable levels of oxidative rancidity and warmed-over flavour on the 5th day of storage. A significant (P < 0.05) interaction between condition and treatment revealed that phosphate treated samples got a higher overall acceptability score (6.33) compared with controls (5.38) in the cold-processed product. A similar trend was observed in the hot-processed group but differences were only marginal between phosphate treated samples (6-36) and their controls (5.84). This indicates that addition of polyphosphate is more desirable in the product processed from post-rigor meat. Interaction between mincing and storage was also significant (P < 0.01) and overall acceptability score dropped from the 1st day (6-86) to the 4th day (5-55) in hand minced samples. Similarly, scores dropped from 6.67 (day 1) to 4.85 (day 4) in machine minced samples but the drop in score was more rapid compared with the hand minced group of samples. This correlates well with a similar trend observed for texture scores discussed above. It may be concluded from these findings that both pre-rigor and chilled lamb meat can be utilised for processing of 'Rista'. However, hotprocessing offers several advantages, such as improved product texture, juiciness and palatability. A comparison of comminution methods revealed that the quality of traditionally minced Rista is superior to the machine minced product. In addition, the use of 0.5% sodium tripolyphosphate improves the quality of such product. Cooked Rista, properly packaged in low density polyethylene bags (0-25 /.~m thickness) can be stored in a satisfactory condition at 4 _+ 1°C for a period of 4 days. REFERENCES Anjaneyulu, A. S. R. (1988). PhD thesis, Indian Veterinary Research Institute, Izatnagar (UP), India. Ansari, N. (1985). Shiraza, J. & K. Acad. Art, Culture and Languages, Srinagar, Kashmir, 22(6), 57. AOAC (1980). Official Methods of Analysis, 13th edn. Association of Official

Studies on processing and refrigerated storage of 'R&ta'

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Analytical Chemists, Washington, D.C. Method nos. 24.003, 24.005, 24.027 and 24,062, pp. 376-84. Baliga, B. R. & Madaiah, N. (1971). J. Food Sci., 36, 609. Bendall, J. R. (1978). Meat Sci., 2, 91. Chattoraj, D. K., Bose, A. N., Sen, M. & Chatterjee, P. (1979). J. Food Sci., 44, 197. Chu, Y. H., Huffman, D. L., Trout, G. R. & Egbert, W. R. (1987). J. Food Sci., 52, 869. Cross, H. R., Berry, B. W. & Muse, D. (1979). J. Food Sci., 44, 1432. Dar, K. P. (1977). Kashmiri Cooking, 1st edn. Vikas Publishing House Private Ltd, New Delhi, pp. 6-10. Huffman, D. L., Cross, H. R., Campbell, K. J. & Cordray, J. (1981). J. Food Sci., 46, 34. ICMSF (1978). Micro-organisms in Foods 1. International Commission for Microbiological Specifications on Foods, University of Toronto Press, Toronto, pp. 105-24. Jacobs, D. K. & Sabranek, J. G. (1980). J. Food Sci., 45, 648. Jay, J. M. (1986). Modern Food Microbiology, 3rd edn. CBS Publishers and Distributors, Delhi, p. 38. Keeton, J. T. (1983). J. Food Sci., 48, 878. Kondaiah, N. & Sharma, N. (1988). lndian J. Meat ScL Technol., 1, 28. King, A. J. & Earl, L. A. (1988). J. Food Sci., 53, 723. Koniecko, E. S. (1979). Hand Book for Meat Chemists, 1st edn. Avery Publishing Group Inc., Wayne, New Jersey, p. 53. Maesso, E. R., Baker, A. A., Hotchkins, D. K., Molins, R. A., Olson, D. G., Walker, H. W. & Merkenich, K. (1970). J. Food Sci., 53, 391. Marcy, J. A., Kraft, A. A., Hotchkins, D. K., Molins, R. A., Olson, D. G., Walker, H. W. & Merkenich, K. (1988). J. Food Sci., 53, 391. Matlock, R. G., Terrel, R. N., Savell, L. W., Rhee, K. S. & Duston, T. R. (1984). J. Food Sci., 49, 1372. McKenzie, D. S. (1964). Prepared Meat Product Manufacture. American Meat Institute, Chicago, p. 60. Molins, R. A., Kraft, A. A., Walker; H. W., Rust, R. E., Olson, D. G. & Merkenich, K. (1987). J. Food Sci., 52, 50. Moore, S. L., Theno, D. M., Anderson, C. R. & Schmidt, G. R. (1976). J. Food Sci., 41, 424. Neer, K. L. & Mandigo, R. W. (1977). J. Food Sci., 42, 728. Ravindranath, G., Varadarajulu, P. &~Reddy, S. K. (1988). lndian J. Meat Sci. Technol., 1, 67. Reagan, J. O., Liou, E. H., Reynolds, A. E. & Carpenter, J. A. (1983). J. Food Sci., 48, 146. Samoon, A. H. & Sharma, N. (1991). J. Food Sci. Technol., 28, 212. Samoon, A. H. & Sharma, N. (1988). lndian J. Meat Sci. Technol., 1, 48. Schmidt, R. G. & Trout, R. G. (1984). In Recent Advances in the Chemistry of Meat, ed. A. J. Bailey. The Royal Society of Chemistry, Burlington House, London, p. 234. Schwartz, W. C., Bender, F. & Everson, C. (1985). Meat Process., Aug., 1985. Schults, G. W., Russel, D. R. & Wierbiecki, E. (1972). J. Food Sci., 37, 860. Sofos, J. (1986). Food Technol., 40(9), 52.

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Snedecor, W. G. & Cochran, W. G. (1968). Statistical Methods, 6th edn. Oxford and IBH Publ. Co., New Delhi, pp. 339-80. Steel, G. D. R. & Torrie, J. H. (1980). Principles and Procedures of Statistics, Int. Students edn. McGraw Hill, New Delhi, pp. 173-5. Steinhauer, J. E. (1983). Dairy and Food Sanitation, 3(7), 244. Stone, H. & Sidel, J. L. (1985). Sensory Evaluation Practices. Tragon Corp., Academic Press, New York, pp. 77, 235. Tarladgis, B. G., Watts, B. M., Younathan, M. T. & Dugan, L. Jr (1960). J. Amer. Oil Chem. Soc., 37(7), 66. Theno, D. M., Siegel, D. G. & Schmidt, G. R. (1978). J. Food Sci., 43, 493. Young, L. L., Lyon, C. E., Searcy, G. K. & Wilson, R. L. (1987). J. Food Sci., 52, 571.

APPENDIX Glossary of Terms and Abbreviations used in Tables 2-8 SE TBA HB CB TM MM ST PT df MSS Conditions Mincings Treatments HB HB HB HB CB CB CB CB

TM ST TM PT M M ST M M PT T M ST T M PT M M ST M M PT

Standard error 2-Thiobarbituric acid value (mg melanoldehyde/1000 g meat) Hot-boned (pre-rigor) Cold-boned (post-rigor) Traditionally minced (hand minced) Machine minced Salt alone treated Phosphate and sodium chloride treated Degrees of freedom Mean sum of squares 1. 2. 1. 2. 1. 2.

Hot-boned Cold-boned Traditionally minced Machine minced Salt alone treated Salt and phosphate treated

Hot-boned, traditionally minced and salt treated Hot-boned, traditionally minced and phosphate treated Hot-boned, machine minced and salt treated Hot-boned, machine minced and phosphate treated Cold-boned, traditionally minced and salt treated Cold-boned, traditionally minced and phosphate treated Cold-boned, machine minced and salt treated Cold-boned, machine minced and phosphate treated